Pump failure is considered to be the primary pathophysiologic defect in cardiogenic shock secondary to acute myocardial infarction. Several investigators have reported mortality in 85% to 95% of patients with this syndrome.1-4 In those with cardiogenic shock accompanied by pulmonary edema, the fatality rate was 100% in a series of 241 patients with acute myocardial infarction studied by E. Greif, according to an oral communication with him on Oct 28, 1968. Available pharmacologic therapies which augment myocardial contractility or raise systemic blood pressure also increase the internal work of the heart and, therewith, its oxygen demand. Use of these agents does not appear to be associated with an increased survival rate.

Since June 1967 a mechanical means of circulatory support for patients in refractory cardiogenic shock, the intraaortic phase-shift balloon pump, has been under clinical trial. Our experimental laboratory studies and initial clinical evaluation indicated that balloon pumping effectively